wightman



(No Model.)

' H. LEMP 82 M. J. WIGHTMAN.

THERMOSTATIG GUT-OUT FOR INGANDESGENT LAMPS.

No. 352,622. Patented Nov. 16, 18-86.

l/Vl/E/VTOHJ By ATTORNEYS WITNESSES} W UNITED STATES PATENT OFFICE.

HERMANN LEMP AND MERLE J. \VIGHTMAN, OF HARTFORD, CONN ECTICUT, I

ASSIGNORS TO THE SCHUYLER ELECTRIC LIGHT COMPANY.

THERMOSTATIC CUT-OUT FOR INCANDESCENT LAMPS.

SPECIFICATION forming part of Letters Patent No. 352,622, dated November16, 1886.

Application filed August 27, 1886. Serial No. 521L992. (No model.)

To all whom it may concern.-

Be it known that we, HERMANN LEMP and MERLE J. W IGIITMAN, citizens ofthe United States, and residents of Hartford, in the county of Hartfordand State of Connectic'ut,haveinvented certain new and usefulThermostatic Cut-Outs for Incandescent Electric lamps, of which thefollowing is a specification.

Our invention relates to the construction of 1c incandescent lamps, andinvolves more particularly features of improvement in the arrangement oiconductors within the lamp,

whereby the lamp is especially adapted for use on circuits carryingheavy currents.

1 The object of our invention is more particularly to so construct thelamp that in case of the rupture of the filament of the same a new pathfor the electric current may be automatically formed so as toshort-circuit or cut out the lamp from the system.

In an application filed of even date herewith we have described severalways of automatically short-circuiting or cutting out an incandescentlamp from the system upon the 2 5 rupture of the filament, by utilizingthe increased temperature developed within the lamp upon the formationof the electric arc to release movable metallic contacts normally heldout of operative position, and which are 0 thereupon brought together toform a new path for the current.

Our present invention involves another application of principle ofthermostatic action within the lamp to accomplish the same result,

5 and is based, primarily, upon the unequal ex pansion of differentkinds of metal under the influencezof heat.

To this end our invention consists of thermostatic expansion pieceslocated within the 0 lamp and in proximity to the filament, and

adapted to establish. an electrical connection between the leading-inconductors upon an increase of temperature due to the rupture of thefilament.

In the accompanying drawings, Figure 1 represents a side elevation of apart of a lamp embodying our invention. Fig-2 is ahorizontal sect-ionthrough the line X X of Fig. 1. Fig. 3 is a section through the sameline showing the relative position of the conductors after the ruptureof the filament by the electric arc. Fig. 4 is a detail View of theleadingin conductor. Fig. 5 is an end elevation of the leading-inconductors with the copper strips Q attached.

In carrying out our invention in the manner herein illustrated theleading-in conductors C C of the lamp A are constructed of platinum, andare preferably formed in the shape of flat rectangular strips, as shown.These conductors enter the lamp in dilierent vertical planes, asindicated in Figs. 2, 3, and 5.

At some point Within the lamp and near the filament the conductors arebrought into immediate proximity by means of horizontal extensions c cof the same material extending, respectively, over the face of theopposite conductors, and in proximity thereto, but out of contacttherewith under the normal condi tions of the lamp- To the outer side ofthese extensions are bolted or riveted the expansion-pieces D D'ofcorresponding size and shape and oppositely attached to theextensions-that is to say, the strip D being bolted or riveted to theextension 0, and the strip Dbeing bolted or riveted to the extension 0,as shown in Figs. 2 and 3,

so that the leading-in conductors with their extensions and the copperstrips form at this point two parallel plates. The expansionpieces D Dare composed of some metal which expands unequally under the influenceof heat as compared with the part of the lamp to which they areattached. As the expansion-pieces are shown in the present case asattached di- 8 5 rectly to the platinum conductors, they are made ofsome metal which expands more than the platinum conductors under theinfluence of heat, preferably copper.

The operation of the device is as follows: 0 \Vhen from any cause thefilament of the lamp is ruptured, an electric arc is thereby formedbetween its broken ends, and there is at once developed a sensibleincrease of heat within the lamp, due to the increased resistance of 5the electric arc. The copper strips and the platinum conductors andextensions being equally subjected to the influence of the heat, thecopper strips,which expand considerably more than the correspondingplatinum surico faces to which they are rigidly attached, tend to warpthe combined mass and force the two platinum surfaces together on eachside of the lampthat is to say, the extension 0 being turned in andforced toward the leading-in conductor 0 in its immediate proximity, andthe extension 0' being-turned in and forced toward the neighboringleading'in conductor 0, as indicated by the arrowsin Fig. 2 and shown inFig. 3, thereby forming a new path for the electric current across thelamp at that point. As the ends of the expansionpieccs which areextended over the body of the leading in conductors are not rigidlyattached thereto,it is clear that those ends of the expansion-pieces arepermitted to expand freely under the influence ofheat, and will have notendency, or very little tendency, to move the conductors themselves,but the movement will be as indicated in Fig. 3.

In this application we have described a lamp which involves the use oftwo expansion-pieces attached, respectively, to the two conductors; butit is evident that the same result could be accomplished by the use of asingle expansionpiece which would produce the whole of the movementnecessary to establish the new path for the current. NVe have also shownthese expansionpieces as attached directly to the leading-in conductors;but it is evident that these pieces might be applied to other devices orparts having connection with .such conductors, the sole purpose of theinvention in this respect being to avail ourselves of the unequalexpansion 05- the different metals in order to establish an electricalconnection between the leading-in conductors upon the increase of heatdue to the rupture of the filament.

*hat we claim as our invention is 1. The combination, with anincandescent lamp, of thermostatic expansion-pieces located within thelamp and in proximity to the filament, and adapted to close a circuitthrough the conductors upon an increase of temperature due to therupture of the filament, as and for the purpose described.

2. The combination, with an incandescent lamp, of thermostaticexpansion-pieces attached to the conductors within the lamp and inproximity to the filament, and adapted to force the same into electricalconnection upon an increase of temperature due to the rupture of thefilament, as and for the purpose described.

3. The combination, with an incandescent lamp, of leading-in conductorsbrought into proximity at some point within the lamp, thermostaticexpansion-pieces attached to such conductors at that point and adaptedto force them into contact upon an increase of temperature due to therupture of the filament, as and for the purpose described.

4. The combination, with an incandescent lamp, of a thermostaticexpansion-piece attached to a leading-in conductor of different materialblJClCflOl'll, whereby such conductor is forced into electricalconnection with the other conductor upon an increase of temperature dueto the rupture of the filament, as and for the purpose described.

Signed at Hartford, in the county of Hart ford and State of Connecticut,this 13th day of August, A. D. 1886.

HERMANN LEMP.

MERLE J. XV IGHTMA N.

Witnesses: A

WM. E. SHEPARD, CHAS. E. D'Us'rIN.

